179,809 research outputs found
Spin-depedent transmission of holes through periodically modulated diluted magnetic semiconductor waveguides
We study spin transport of holes through stubless or stubbed waveguides
modulated periodically by diluted magnetic semiconductor (DMS) sections of
width b1 . Injected holes of up (down) spin feel a periodically modulated
barrier (well) potential in the DMS sections and have different transmission
(T) coefficients. T oscillates with b1 for spin-down and decreases fast for
spin-up holes while the relative polarization Pr depends nearly periodically on
the stub height. Using asymmetric stubs leads to a nearly square-wave pattern
in T and to wide plateaus in Pr . T oscillates with the length between the DMS
sections. With two DMS sections per unit, T shows periodically wide gaps for
spin-down holes when a DMS width is varied. The results can be used to create
efficient spin filters.Comment: 5figure
Spin-dependent transmission in waveguides with periodically modulated strength of the spin-orbit interaction
The electron transmission is evaluated through waveguides, in which the
strength of the spin-orbit interaction(SOI) is varied periodically,
using the transfer-matrix technique. It is shown that exhibits a {\it
spin-transistor} action, as a function of or of the length of one of
the two subunits of the unit cell, provided only one mode is allowed to
propagate in the waveguide. A similar but not periodic behavior occurs as a
function of the incident electron energy. A transparent formula for through
one unit is obtained and helps explain its periodic behavior. The structure
considered is a good candidate for the establishment of a realistic spin
transistor
Plasmon spectrum of two-dimensional electron systems with Rashba spin-orbit interaction
The dielectric function and plasmon modes of a two-dimensional electron gas
(2DEG) are studied in single- and double-quantum-well structures with Rashba
spin-orbit interaction (RSOI) in the framework of the random-phase
approximation. The RSOI splits each parabolic energy subband of a 2DEG into two
nonparabolic spin branches and affects the electronic many-body correlation and
dielectric properties of the 2DEG. The influence of the RSOI on the 2DEG
plasmon spectrum in single quantum wells appear mainly in three ways: 1) an
overall frequency lowering due to the energy band deformation; 2) a weak
frequency oscillation stemming from the spin-split energy band; and 3)an
enhancement of the Landau damping as a result of the emerging of the
inter-branch single-particle-excitation spectrum. In double quantum wells, the
above effects are enhanced for the optic plasmon mode but diminished for the
acoustic one.Comment: 7 figure
Ballistic spin transport through electronic stub tuners: spin precession, selection, and square-wave transmission
Ballistic spin transport is studied through electronic tuners with double
stubs attached to them. The spins precess due to the spin-orbit interaction.
Injected polarized spins can exit the structure polarized in the opposite
direction. A nearly square-wave spin transmission, with values 1 and 0, can be
obtained using a periodic system of symmetric stubs and changing their length
or width. The gaps in the transmission can be widened using asymmetric stubs.
An additional modulation is obtained upon combining stub structures with
different values of the spin-orbit strength.Comment: 3 pages, 4 figure
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